1. Field of the Invention
The present invention relates to vacuum scroll pumps.
2. Description of the Related Art
A scroll pump is a type of pump that includes a stationary plate scroll having a spiral stationary scroll blade, an orbiting plate scroll having a spiral orbiting scroll blade, and an eccentric driving mechanism to which the orbiting plate scroll is coupled. The stationary and orbiting scroll blades are nested with a radial clearance and predetermined relative angular positioning such that a pocket (or pockets) is delimited by and between the blades. The orbiting scroll plate and hence, the orbiting scroll blade, is driven by the eccentric driving mechanism to orbit about a longitudinal axis of the pump passing through the axial center of the stationary scroll blade. As a result, the volume of the pocket(s) delimited by the scroll blades of the pump is varied as the orbiting scroll blade moves relative to the stationary scroll blade. The orbiting motion of the orbiting scroll blade also causes the pocket(s) to move within the pump head assembly such that the pocket(s) is selectively placed in open communication with an inlet and outlet of the scroll pump.
In an example of such a scroll pump, the motion of the orbiting scroll blade relative to the stationary scroll blade causes a pocket sealed off from the outlet of the pump and in open communication with the inlet of the pump to expand. Accordingly, fluid is drawn into the pocket through the inlet. Then the pocket is moved to a position at which it is sealed off from the inlet of the pump and is in open communication with the outlet of the pump, and at the same time the pocket is contracted. Thus, the fluid in the pocket is compressed and thereby discharged through the outlet of the pump.
In the case of a vacuum-type of scroll pump, the inlet of the pump is connected to a system that is to be evacuated, e.g., a system including a processing chamber in which a vacuum is to be created and/or from which gas is to be discharged.